JPH0750275A - Integrated circuit and its thin film forming equipment - Google Patents

Abstract

PURPOSE:To obtain a barrier layer wherein excellent step coverage can be ensured, and a wiring layer can be suitably buried in a contact hole. CONSTITUTION:From a silicon substrate 1 toward a wiring layer 3, a barrier layer 5 is constituted of a titanium layer 5a, a titanium nitride layer 5b, and a silicon layer 5c which forms alloy with aluminum of the wiring layer 3 and lowers the melting point of aluminum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated circuit in which an aluminum wiring layer is formed on a substrate via a barrier layer and a thin film forming apparatus therefor, and is particularly characterized by the structure of the barrier layer.

[0002]

2. Description of the Related Art Conventionally, in order to prevent the wiring material of a wiring layer from diffusing into the silicon substrate at the boundary between the silicon substrate of the LSI (Large Scale Integrated Circuit) and the wiring layer,
In addition, a barrier layer or an adhesion layer made of a material such as titanium nitride is formed in order to secure electrical contact between the wiring material and the silicon substrate. As the miniaturization of LSI progresses, the design rule reaches half micron, and a method of forming a wiring layer on the barrier layer with a good burying property is required, which can secure good barrier properties and contacts.

FIG. 5 is a sectional view showing the structure of a conventional integrated circuit of this kind shown in, for example, "Semicon Kansai / Kyoto Technical Seminar 90 Lecture Proceedings" (June 22.1990). In the figure, 1 is a silicon substrate, 2 is an insulating layer formed on the silicon substrate 1, and a contact hole 2
a is arranged at a predetermined position. A wiring layer 3 is formed on the insulating layer 2 so as to be connected to the silicon substrate 1 via the contact hole 2a, and a wiring layer 4 made of an alloy of aluminum, silicon, copper or the like is provided.
Is a barrier layer made of titanium nitride, which is interposed between and.

The barrier layer 4 of the conventional integrated circuit configured as described above is formed by forming the insulating layer 2 on the silicon substrate 1 and then depositing titanium nitride into a predetermined layer on the insulating layer 2 by, for example, a sputtering method or a CVD method. It is formed by coating only the thickness.

[0005]

Since the conventional integrated circuit is constructed as described above, when the design rule of the barrier layer 4 becomes smaller and the thickness of the barrier layer 4 becomes thinner, the in-plane characteristic variation becomes remarkable. Or the good step coverage cannot be secured in the contact hole 2a, the interaction between the silicon substrate 1 and the wiring layer 3 and the diffusion function cannot be suppressed, and the wiring is formed after the barrier layer 4 is coated. There is a problem that the layer 3 cannot be embedded in the contact hole 2a.

The present invention has been made in order to solve the above problems, and has a barrier layer which can secure good step coverage and can satisfactorily bury a wiring layer in a contact hole. An object is to provide an integrated circuit and a thin film forming apparatus thereof.

[0007]

According to a first aspect of the present invention, in an integrated circuit, a barrier layer is formed from a substrate toward an aluminum wiring layer to form an alloy with a titanium layer, a titanium nitride layer and an aluminum wiring layer. It is composed of a metal layer that lowers the melting point of aluminum.

In the integrated circuit according to the second aspect of the present invention, the barrier layer is made of a titanium layer, a titanium nitride layer and aluminum and a metal for lowering the melting point of aluminum in the aluminum wiring layer from the substrate toward the aluminum wiring layer. The aluminum alloy layer is formed.

According to a third aspect of the present invention, in the second aspect, the metal for lowering the melting point of aluminum forming the aluminum alloy layer and aluminum of the aluminum wiring layer is simultaneously deposited by the ICB method. It is the one.

According to a fourth aspect of the present invention, there is provided a thin film forming apparatus for an integrated circuit, wherein an ionized vapor or ionized cluster of titanium is placed on a substrate in a vacuum chamber which is maintained at a predetermined vacuum degree and accommodates the substrate. A first cluster-type ion source for irradiating and depositing on a substrate, and a second cluster-type ion source for irradiating and depositing an ionized vapor or ionized cluster of a metal that lowers the melting point of aluminum by forming an alloy with aluminum on the substrate. A cluster type ion source, a third cluster type ion source for irradiating and vaporizing aluminum ionized vapor or ionized clusters on the substrate, and a nitrogen gas introducing means for introducing nitrogen gas near the substrate were provided. It is a thing.

[0011]

The metal layer disposed on the uppermost layer of the barrier layer of the integrated circuit according to claim 1 of the present invention reacts with aluminum of the aluminum wiring layer to form an alloy when the wiring layer is formed. Lowers the melting point of.

Further, the aluminum alloy layer disposed on the uppermost layer of the barrier layer of the integrated circuit according to claim 2 of the present invention reacts with aluminum of the aluminum wiring layer to form an alloy when the wiring layer is formed, Lower the melting point of the aluminum wiring layer.

Further, the aluminum and the metal forming the aluminum alloy layer provided on the uppermost layer of the barrier layer of the integrated circuit according to claim 3 of the present invention are simultaneously vapor-deposited by the ICB method.

The first cluster type ion source of the thin film forming apparatus for an integrated circuit according to claim 4 of the present invention forms a titanium layer forming a part of the barrier layer, and the nitrogen gas introducing means is titanium. A titanium nitride layer is formed by introducing nitrogen near the surface of the layer, the second cluster type ion source forms a metal layer or an aluminum alloy layer, and the third cluster type ion source forms an aluminum wiring. Form the layers.

[0015]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. 1 is a sectional view showing the structure of an integrated circuit according to a first embodiment of the present invention. In the figure, the same parts as those of the conventional device shown in FIG. 5
Is a barrier layer interposed between the silicon substrate 1 and the wiring layer 3, and is composed of a titanium layer 5a, a titanium nitride layer 5b and a silicon layer 5c which are sequentially arranged from the silicon substrate 1 side toward the wiring layer 3 side. Has been done.

FIG. 2 is a diagram schematically showing a schematic configuration of a thin film forming apparatus for forming a thin film of the integrated circuit in FIG. In the figure, 11 is a vacuum chamber held at a predetermined vacuum degree, 12 is a rotary holding mechanism 13 above the vacuum chamber 11.
A substrate rotatably held by the substrate, 14 is the substrate 1
A heater for heating 2; 15 is a gas introducing pipe that penetrates the vacuum chamber 11 and has an opening near the surface of the substrate 12 for introducing nitrogen gas; 16 is a gas introducing pipe for introducing nitrogen gas. Flow rate adjustment valve to adjust the flow rate, 1
Reference numeral 7 denotes a vacuum exhaust system which is connected to a lower portion of the vacuum chamber 11 for adjusting the degree of vacuum in the vacuum chamber 11.

Reference numerals 18, 19, 20 denote shutters for opening and closing the flow of the electron beam, and 21, 22, 23 denote crucibles 21, respectively.
titanium 21b as a vapor deposition material in a, 22a, 23a,
Each of the shutters 18 holds a silicon 22b and an aluminum 23b, and an ionized vapor or ionized cluster of each vapor deposition material 21b, 22b, 23b is provided in each shutter 18,
First, second and third cluster type ion sources for irradiating the substrate 12 via 19, 20.

Further, 24 is a nozzle formed above the crucible 21a, 25 is a heating filament disposed around the crucible 21a, and 26 is heat disposed so as to cover the periphery of the heating filament 25. These two with a shield plate
A vapor generating source 27 is composed of 1a, 21b, and 24-26. 28 is a cluster (lumped atomic group) formed by vapor of titanium 21b ejected from the nozzle 24,
Reference numeral 29 is an electron beam emitting filament for emitting an electron beam, 30 is an electron beam extracting electrode for extracting and accelerating electrons from the electron beam emitting filament 29, 31
Is a heat shield plate arranged so as to cover the periphery of the electron beam emitting filament 29, and these 29, 30, 31 constitute a cluster ionization means 32.

Further, 33 is an acceleration electrode for accelerating the ionized cluster 40 ionized by the cluster ionization means 32 with an electric field to give kinetic energy, 34 is the first AC power source for the heating filament 25, and 35 is the crucible 21a. Is positively biased with respect to the heating filament 25, 36 is a second AC power source for the electron beam emission filament 29, and 37 is the potential of the electron beam emission filament 29.
Is a second DC power source that is biased negatively with respect to the third DC power source 38 that biases the potentials of the crucible 21a and the electron beam extraction electrode 30 positively with respect to the acceleration electrode 33. The power supply device 39 is configured. Then, the vapor generation source 27 and the cluster ionization means 32 driven by the power supply device 39.
The above-mentioned first cluster type ion source 21 is constituted by the above. The second and third cluster-type ion sources 22 and 23 are similar to the first cluster-type ion source 21, and therefore description thereof will be omitted, but each of the cluster-type ion sources 21 to 23 is as shown in FIG. , Are arranged symmetrically with respect to the substrate 12.

Next, the operation of the thin film forming apparatus configured as described above will be described. First, the inside of the vacuum chamber 11 is evacuated by the vacuum evacuation system 17 to a vacuum degree of about 1 × 10 ⁻⁶ Torr, and then the substrate 12 is heated by the heater 14, and the rotation holding mechanism 13 indicates an arrow in FIG. Rotate in the direction shown. Then, each shutter 18, 1
With 9 and 20 closed, titanium 21b as a vapor deposition material,
Electrons emitted from the heating filament 25 are supplied to the respective crucibles 21a, 22a and 23a respectively filled with silicon 22b and aluminum 23b, that is, in the case of the first cluster type ion source 21, to the crucible 21a. 1 is accelerated by the electric field applied from the DC power supply 35, and the vapor pressure in the crucible 21a is several To while colliding.
Heat to rr.

By this heating, the titanium 21b in the crucible 21a is evaporated and jetted from the nozzle 24 into the vacuum chamber 11. The vapor of the titanium 21b thus injected causes a supercooled state due to adiabatic expansion when passing through the nozzle 24, and forms a cluster 28. The cluster 28 is partially ionized by the electron beam emitted from the electron beam filament 29 to become an ionized cluster 40. This ionized cluster 40 is accelerated by the electric field formed by the acceleration electrode 33 together with the remaining non-ionized cluster 28. If the shutter 18 is switched to the open state in this state, the ionized clusters 40 and the clusters 28 will be separated from the substrate 12.
By irradiating and colliding with the surface of, the thin film of titanium 21b, that is, the titanium layer 5a as shown in FIG. 1, is formed on the surface of the substrate 12.

Next, the flow rate adjusting valve 16 is opened, nitrogen gas is introduced into the vacuum chamber 11 through the gas introducing pipe 15 near the surface of the substrate 12, and this nitrogen gas and the ionized clusters 40 and 28 to be irradiated are applied to the substrate. The reaction is carried out on 12 to form a titanium nitride layer 5b on the titanium layer 5a as shown in FIG.

Then, the flow rate adjusting valve 16 is closed to stop the supply of the nitrogen gas into the vacuum chamber 11, and then the shutter 18 is closed and the shutter 19 is opened, whereby the first cluster type ion source 21 By the same action as the case, the ionized clusters and clusters of the silicon 22b from the second cluster type ion source 22 are irradiated to the surface of the substrate 12 and collide with each other, so that the titanium nitride layer 5b as shown in FIG. A silicon layer 5c is formed on the titanium layer 5a and the titanium nitride layer 5
The barrier layer 5 is composed of b and the silicon layer 5c.

After that, when the shutter 19 is closed and the shutter 20 is opened, the ionized clusters and clusters of aluminum 23b from the third cluster ion source 23 are irradiated on the surface of the substrate 12 and collide with each other. As shown in FIG. 1, the wiring layer 3 is formed on the silicon layer 5c to form an integrated circuit.

According to the integrated circuit of the first embodiment of the present invention configured as described above, the contact resistance from the silicon substrate 1 side to silicon is small and the adhesion is high in the length direction of the contact hole 2a. High titanium layer 5
a, a titanium nitride layer 5b having a good barrier property between silicon and an aluminum wiring material, and a silicon layer having good adhesion and wettability with the aluminum wiring material and being easily alloyed with aluminum. 5c are respectively arranged and the barrier layer 5 has a three-layer structure of these layers 5a, 5b and 5c.

When the substrate is heated when the wiring layer 3 is formed, the outermost silicon layer 5c of the barrier layer 5 reacts with aluminum of the wiring layer 3 and alloys to lower the melting point of the wiring layer 3 so that reflow occurs. As a result, the burying property is improved even in the fine contact hole 2a, and an integrated circuit having a good electrical contact property and a good barrier property can be obtained.

Example 2. In the first embodiment, the silicon layer 5c is applied as a metal layer that lowers the melting point of aluminum by forming an alloy with aluminum of the wiring layer 3. However, the present invention is not limited to this, and silicon is used instead. Needless to say, the same effect can be obtained by applying germanium, titanium or the like.

Example 3. Fourth Embodiment FIG. 4 is a sectional view showing the structure of an integrated circuit according to a third embodiment of the present invention. In the figure,
The same parts as those in the first embodiment shown in FIG. 41a and 41b are 5a and 5b shown in FIG.
Titanium layer and titanium nitride layer similar to the above, 41c is an alloy layer of aluminum and silicon, and each of these layers 41a,
The barrier layer 41 is formed by 41b and 41c.

Next, a case will be described in which the thin film formation of the integrated circuit according to the third embodiment configured as described above is performed using the thin film forming apparatus shown in FIG. First, in the same manner as in Example 1, after forming the titanium layer 41a and the titanium nitride layer 41b, the flow rate adjusting valve 16 is closed to stop the supply of nitrogen gas into the vacuum chamber 11, and the shutter 18 is opened.
And the remaining shutters 19 and 20 are opened, the ionized clusters and clusters of silicon 22b from the second cluster ion source 22 and the aluminum 23b from the third cluster ion source 23 are ionized. Clusters and clusters
By irradiating and colliding with the substrate 12, respectively,
As shown in FIG. 4, an alloy layer 41 of aluminum and silicon
Barrier layer 41 is formed by forming c on titanium nitride layer 41b.

After that, the shutter 19 is closed and only the shutter 20 is opened, and the ionized clusters and clusters of the aluminum 23a from the third cluster ion source 23 are irradiated on the substrate 12 to collide with each other, whereby the alloy layer 41c. The wiring layer 3 is formed on the upper part of the integrated circuit.

In the integrated circuit according to the third embodiment having the above-described structure, the alloy layer 41c lowers the melting point of the wiring layer 3 during heating of the substrate during formation of the wiring layer 3 and facilitates reflow. Is improved, and the remaining layers 41a and 41b also improve the electrical contact and barrier properties.

Example 4. In the third embodiment, the alloy layer 41c is made of an alloy of aluminum and silicon. However, instead of the silicon 22b in the crucible 22a shown in FIG. 2, for example, germanium, titanium or the like is used, and aluminum and germanium are used. The same effect as in the third embodiment can be obtained by using the above alloy or an alloy of aluminum and titanium.

[0033]

As described above, according to claim 1 of the present invention, an alloy is formed by forming a barrier layer from a substrate toward an aluminum wiring layer with a titanium layer, a titanium nitride layer and aluminum of the aluminum wiring layer. Since it is composed of the metal layer that lowers the melting point, it is possible to provide an integrated circuit that can secure good step coverage and can satisfactorily bury the wiring layer in the contact hole.

According to a second aspect of the present invention, the barrier layer is formed of a titanium layer, a titanium nitride layer and aluminum from the substrate toward the aluminum wiring layer and a metal that lowers the melting point of aluminum in the aluminum wiring layer. Since it is composed of the aluminum alloy layer, it is possible to provide an integrated circuit in which good step coverage can be secured and the wiring layer can be satisfactorily embedded in the contact hole.

According to a third aspect of the present invention, in the second aspect, the metal that lowers the melting point of aluminum forming the aluminum alloy layer and aluminum of the aluminum wiring layer is simultaneously deposited by the ICB method. Therefore, it is possible to provide an integrated circuit in which good step coverage can be secured, the wiring layer can be satisfactorily embedded in the contact hole, and the number of manufacturing steps can be reduced.

According to a fourth aspect of the present invention, an ionized vapor or ionized cluster of titanium is irradiated onto the substrate for vapor deposition in a vacuum chamber which is held at a predetermined degree of vacuum and accommodates the substrate. A first cluster-type ion source, and a second cluster-type ion source for irradiating a substrate with ionized vapor or ionized clusters of a metal that lowers the melting point of aluminum by forming an alloy with aluminum for vapor deposition Good step coverage because a third cluster type ion source for irradiating the substrate with ionized vapor or ionized clusters of aluminum for vapor deposition and a nitrogen gas introducing means for introducing nitrogen gas in the vicinity of the substrate are provided. Thin film capable of producing an integrated circuit in which the wiring layer can be secured and the wiring layer can be satisfactorily embedded in the contact hole. Can provide deposition apparatus, it is possible to exert a practically superior effect.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of an integrated circuit according to a first embodiment of the present invention.

FIG. 2 is a diagram schematically showing a schematic configuration of a thin film forming apparatus for forming a thin film of the integrated circuit in FIG.

3 is a diagram schematically showing a positional relationship between each cluster type ion source and a substrate in the thin film forming apparatus shown in FIG.

FIG. 4 is a diagram schematically showing a configuration of an integrated circuit according to a third embodiment of the present invention.

FIG. 5 is a diagram schematically showing a configuration of a conventional integrated circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Insulating layer 2a Contact hole 3 Wiring layer 5,41 Barrier layer 5a, 41a Titanium layer 5b, 41b Titanium nitride layer 5c Silicon layer (metal layer) 11 Vacuum tank 12 Substrate 13 Rotation holding mechanism 14 Heating heater 15 Gas introduction Tubes 18, 19, 20 Shutters 21 First cluster type ion source 21a, 22a, 23a Crucible 21b Titanium 22b Silicon 23b Aluminum 41 Barrier layer 41c Alloy layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01L 21/768

Claims (4)

[Claims] 1. In an integrated circuit in which an aluminum wiring layer is formed on a substrate via a barrier layer, the barrier layer includes a titanium layer, a titanium nitride layer and an aluminum wiring layer from the substrate toward the aluminum wiring layer. An integrated circuit comprising an alloy with aluminum to form a metal layer which lowers the melting point of aluminum. 2. In an integrated circuit in which an aluminum wiring layer is formed on a substrate via a barrier layer, the barrier layer is a titanium layer, a titanium nitride layer and aluminum and the aluminum wiring from the substrate toward the aluminum wiring layer. An integrated circuit comprising an aluminum alloy layer formed of a metal that lowers the melting point of aluminum in the layer. 3. The integrated circuit according to claim 2, wherein the metal forming the aluminum alloy layer and the metal for lowering the melting point of aluminum in the aluminum wiring layer are simultaneously deposited by the ICB method. 4. A first chamber for irradiating an ionized vapor or ionized cluster of titanium onto the substrate in a vacuum chamber, which is maintained at a predetermined degree of vacuum and accommodates the substrate, for vapor deposition.
And a second cluster type ion source for irradiating and vaporizing an ionized vapor or ionized cluster of a metal that lowers the melting point of aluminum by forming an alloy with aluminum on the substrate. A third cluster type ion source for irradiating and vaporizing the ionized vapor or ionized clusters on the substrate, and a nitrogen gas introducing means for introducing nitrogen gas in the vicinity of the substrate. Thin film forming equipment for integrated circuits.